Sandwich constructions are the most commonly used structures in aircraft and navy industries, traditionally. These structures are made up of the face sheets and the core, where the face sheets will be taking the load and is connected to other structural members, while the soft core material, will be used to absorb energy during impact like situation. Thus, sandwich constructions are mainly employed in light weight structures where the high energy absorption capability is required. Generally the face sheets will be thin, made up of either metallic or composite material with high stiffness and strength, while the core is light in weight, made up of soft material. Cores generally play very crucial role in achieving the desired properties of sandwich structures, either through geometric arrangement or material properties or both. Foams are in extensive use nowadays as core material due to the ease in manufacturing and their low cost. They are extensively used in automotive and industrial field applications as the desired foam density can be fabricated by adjusting the mixing, curing and heat sink processes. Modeling of sandwich beams play a crucial role in their design with suitable finite elements for face sheets and core, to ensure the compatibility between degrees of freedom at the interfaces. Unless the mathematical model simulates the physics of the model in terms of kinematics, boundary and loading conditions, results predicted will not be accurate. Accurate models helps in obtaining an efficient design of sandwich beams. In Structural Health Monitoring studies, the responses under the impact loading will be captured by carrying out the wave propagation analysis. The loads applied will be for a shorter duration (in the orders of micro seconds), where higher frequency modes will be excited. Wavelengths at such high frequencies are very small and hence, in such cases, very fine mesh generally is employed matching the wavelength requirement of the propagating wave. Traditional Finite element softwares takes enormous time and computational e ort to provide the solution. Various possible models and modeling aspects using the existing Finite element tools for wave propagation analysis are studied in the present work. There exists a huge demand for an accurate, efficient and rapidly convergent finite elements for the analysis of sandwich beams. E orts are made in the present work to address these issues and provide a solution to the sandwich user community. Super convergent and Spectral Finite sandwich Beam Elements with metallic or composite face sheets and soft core are developed. As a philosophy, the sandwich beam finite element is constructed with the combination of two beams representing the face sheets (top and bottom) at their neutral axis. The core effects are captured at the interface boundaries in terms of shear stress and normal transverse stress. In the case of wave propagation analysis, the equations are coupled in time domain and spatial domain and solving them directly is a difficult task. In Spectral Finite Element Method(SFEM), the displacement functions are derived by solving the transformed governing equations in the frequency domain. By transforming them and forces from time domain to frequency domain, the coupled partial differential equations will become coupled ordinary differential equations. These equations in frequency domain, can be solved exactly as they are normally ordinary differential equation with constant coefficients with frequency entering as a parameter. These solutions will be used as interpolating functions for spectral element formulation and in this respect it differs from conventional FE method wherein mostly polynomials are used as interpolating functions. In addition, SFEM solutions are expressed in terms of forward and backward moving waves for all the degrees of freedom involved in the formulations and hence, SFEM provides faster and efficient solutions for wave propagation analysis. In the present work, strong form of the governing differential equations are derived for a given system using Hamilton's principle. Super Convergent elements are developed by solving the static part of the governing differential equations exactly and hence the stiffness matrix derived is exact for point static loads. For wave propagation analysis, as the mass is not exactly represented, these elements are required in the optimal numbers for getting good results. The number of these elements required are generally much lesser than the number of elements required using traditional finite elements since the stiffness distribution is exact. Spectral elements are developed by solving the governing equations exactly in the frequency domain and hence the dynamic stiffness matrix derived is exact for the dynamic loads. Hence, one element between any two joints is enough to solve the whole system under impact loads for simple structures. Developing FE for sandwich beams is quiet challenging. Due to small thickness, the face sheets can be modeled using 1D idealization, while modeling of large core requires 2-D idealization. Hence, most finite or spectral elements requires stitching of these two idealizations into 1-D idealization, which can be accomplished in a variety of ways, some of which are highlighted in this thesis. Variety of finite and spectral finite elements are developed considering Euler and Timoshenko beam theories for modeling the sandwich beams. Simple element models are built with rigid core in both the theories. Models are also developed considering the flexible core with the variation of transverse displacements across depth of the core. This has direct influence on shear stress variation and also transverse normal stress in the core. Simple to higher order models are developed considering different variations in shear stress and transverse normal stress across depth of the core. Development of super convergent finite Euler Bernoulli beam elements Eul4d (4 dof element), Eul10d (10 dof element) are explained along with their results in Chapter 2. Development of different super convergent finite Timoshenko beam elements namely Tim4d (4 dof), Tim7d (7 dof), Tim10d (10 dof) are explained in Chapter 3. Validation of Euler Bernoulli and Timoshenko elements developed in the present work is carried out with test cases available in the open literature for displacements and free vibration frequencies are presented in Chapter 2 and Chapter 3. The results indicates that all developed elements are performing exceedingly well for static loads and free vibration. Super convergence performance for the elements developed is demonstrated with related examples. Spectral elements based on Timoshenko theory STim7d, STim6d, STim6dF are developed and the wave propagation characteristics studies are presented in Chapter 4. Euler spectral elements are derived from Timoshenko spectral elements by enforcing in finite shear rigidity, designated as SEul7d, SEul6d, SEul6dF and are presented. E orts were made in this present work to model the horizontal cracks in top or bottom face sheets using the spectral elements and the methodology is presented in Chapter 4. Wave propagation analysis using general purpose software N AST RAN and the super convergent as well as spectral elements developed in this work, are discussed in detail in Chapter 5. Modeling aspects of sandwich beam in N AST RAN using various combination of elements available and the performance of four possible models simulated were studied. Validation of all four models in N AST RAN, Super convergent Euler, Timoshenko and Spectral Timoshenko finite elements was carried out by simulating a homogenous I beam by comparing the longitudinal and transverse responses. Studies were carried out to find out the response predictions of a sandwich beam with soft core and all the predictions were compared and discussed. The responses in case of cracks in top or bottom face sheets under the longitudinal and transverse loading were studied in this chapter. In Chapter 6, Parametric studies were carried out for bringing out the sensitiveness of the important specific parameters in overall behaviour and performance of a sandwich beam, using Super convergent and Spectral elements developed. This chapter clearly brings out the various aspects of design of sandwich beam such as material selection of core, geometrical configuration of overall beam and core. Effects of shear modulus, mass density on wave propagation characteristics, effects of thick or thin cores with reference to the face sheets and dynamic effects of core are highlighted. Wave propagation characteristics studies includes the study of wave numbers, group speeds, cut off frequencies for a given configuration and identification of frequency zone of operations. The recommendations for improvement in design of sandwich beams based on the parametric studies are made at the end of chapter. The entire thesis, written in seven Chapters, presents a unified treatment of sandwich beam analysis that will be very useful for designers working in the area.

Ce projet de maîtrise s'inscrit dans le cadre d'un projet CRIAQ en collaboration avec l’École Polytechnique et quatre partenaires industriels (Bell Helicopters, Bombardier Aerospace, Pratt & Whitney Canada et Artec technologies). Le projet a pour but de développer une nouvelle technologie qui intègre, dès la phase de conception, des éléments amortissants SPADD (Smart Passive Damping Device) dans les structures sandwich-NIDA (une structure en forme de nids d'abeilles). L’objectif est la réduction de la transmission solidienne des vibrations mécaniques ainsi que la diminution de la transmission acoustique du bruit. Les travaux de recherche présentés dans cette maîtrise portent sur le développement d’une approche simple et robuste pour la caractérisation expérimentale de la réponse vibroacoustique des structures sandwich-NIDA avec amortissement SPADD intégré, lorsqu’elles sont soumises à diverses sollicitations. Cette étude, largement guidée par l’expérimentation, a nécessité la conception et la réalisation de nombreux bancs d’essai afin de comprendre et de mesurer les divers phénomènes pour caractériser ces nouvelles structures sandwich-NIDA avec amortissement intégré. L’étude expérimentale a permis de mettre en évidence un gain de 2 à 4 dB au niveau vibratoire et de 1.5 dB au niveau acoustique pour les panneaux NIDA avec amortissement intégré. Enfin, les bancs d’essai proposés ont permis de caractériser les structures sandwich (NIDA) avec amortissement intégré.

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

Previous work in the Rosenberg group showed that the half-sandwich complexes Ru(η5-indenyl)Cl(PR2H)(PPh3) (2i), where R = cyclohexyl (Cy), isopropyl (Pri), phenyl (Ph), para-tolyl (Tolp), react with the strong, bulky base KOBut to give highly reactive complexes Ru(η5-indenyl)(PR2)(PPh3) (6i) containing a ruthenium-phosphorus double bond, Ru=PR2. The reactions of these phosphido complexes 6i with some reagents, such as alkenes, carbon monoxide and dihydrogen, illustrate their rich and varied reactivity. To better understand the mechanisms of these reactions (whether the indenyl effect is necessary), synthesis of analogous secondary phosphine complexes containing the pentamethylcyclopentadienyl (Cp*) ligand, Ru(η5-Cp*)Cl(PPh3)(PR2H) (2) were prepared via ligand substitution at Ru(η5-Cp*)Cl(PPh3)2 (1). Cp* phosphido complexes Ru(η5-Cp*)(PR2)(PPh3) (6) were generated in situ and their reactivity was investigated to see if they behaved similarly to the indenyl complexes. Experimental evidence in this thesis suggests that variable hapticity is not necessary in our indenyl system. In addition, these experimental evidence highlights enhanced lability of ligand at the bulky Cp*Ru fragment and higher Bronsted basicity of the phosphido ligand (PR2-) in Cp* phosphido 6 relative to the indenyl analogues 6i. / Graduate / 2017-12-11 / 0488 / yangjin@uvic.ca

Axxor is one the main leader in paper honeycomb production by supplying automotive, furniture, and door manufacturers. Paper honeycomb material holds the lead over any existing cores in performance, price and density ratio. The main drawback of PHC products is its lack of water/fire resistance which reduces significantly its scope of applications. Consequently, the Axxor company intends to perform a new type of product which could withstand a water exposition: impregnated paper honeycomb. By coating the paper honeycomb cellulose fibers, the mechanical properties are significantly improved with three times higher compressive strength compared to PHC. Two impregnated resins have been selected for a potential large scale production: Epoxy and Polyurethane resins. The totality of IPHC is produced through two processes which are a manual impregnation performed by hand or a continuous impregnation performed by an impregnation machine. With these independent variables in mind, this study concerns the degree of water resistance by comparing three IPHC samples: - Epoxy IPHC performed with handmade impregnation - Polyurethane IPHC performed with handmade impregnation - Polyurethane IPHC performed with the impregnation machine (higher resin content) By using the available characterization devices, water resistance is defined by measuring the decreases of the mechanical performances depending on the remaining water content in each samples.

Kong, Yu Chau = La₂/₃Ca₁/₃MnO₃/Y₂O₃和La₂/₃Ca₁/₃MnO₃/Gd₂O多層薄膜及其三文治結構的傳導特性之研究 / 江如秋. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references. / Abstract also in Chinese. / Kong, Yu Chau = La₂/₃Ca₁/₃MnO₃/Y₂O₃ he La₂/₃Ca₁/₃MnO₃/Gd₂O duo ceng bo mo ji qi san wen zhi jie gou de chuan dao te xing zhi yan jiu / Jiang Ruqiu. / Abstract --- p.i / 論文摘要 --- p.ii / Acknowledgements --- p.iii / Table of Contents --- p.iv / List of Figures --- p.vii / List of Tables --- p.x / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Introduction to Magnetoresistance --- p.1 / Chapter 1.1.1 --- Anisotropic magnetoresistance (AMR) --- p.3 / Chapter 1.1.2 --- Giant magnetoresistance (GMR) --- p.3 / Chapter 1.1.3 --- Colossal magnetoresistance (CMR) --- p.5 / Chapter 1.1.4 --- Tunneling magnetoresistance (TMR) --- p.7 / Chapter 1.2 --- Possible origins of CMR in doped manganite --- p.8 / Chapter 1.2.1 --- Double exchange mechanism --- p.10 / Chapter 1.2.2 --- Jahn-Teller (JT) distortion --- p.14 / Chapter 1.2.3 --- Tolerance factor --- p.16 / Chapter 1.2.4 --- Charge Ordering and percolation theory --- p.18 / Chapter 1.3 --- Motivation --- p.21 / Chapter 1.4 --- Literature Review --- p.23 / Chapter 1.4.1 --- Multilayers --- p.23 / Chapter 1.4.2 --- Junction --- p.25 / Chapter 1.5 --- Scope of this thesis --- p.26 / References --- p.27 / Chapter Chapter 2 --- Instrumentation / Chapter 2.1 --- Thin film deposition --- p.30 / Chapter 2.1.1 --- Facing target sputtering (FTS) --- p.31 / Chapter 2.1.2 --- Vacuum system --- p.33 / Chapter 2.2 --- Oxygen annealing --- p.35 / Chapter 2.3 --- Characterization --- p.35 / Chapter 2.3.1 --- Alpha step profilometer --- p.35 / Chapter 2.3.2 --- X-ray diffraction (XRD) --- p.36 / Chapter 2.3.3 --- Transport measurement --- p.39 / Reference --- p.41 / Chapter Chapter 3 --- Epitaxial growth of La2/3Ca1/3MnO3 and rare earth oxide single layer thin films / Chapter 3.1 --- Introduction --- p.42 / Chapter 3.2 --- Preparation of sputtering targets of rare earth metal and La2/3Ca1/3MnO3 --- p.42 / Chapter 3.3 --- Epitaxial growth of LCMO and Re2O3 thin film --- p.44 / Chapter 3.3.1 --- Substrate materials --- p.44 / Chapter 3.3.2 --- Deposition conditions --- p.45 / Chapter 3.3.3 --- Deposition procedures --- p.48 / Chapter 3.4 --- Characterization of single layer thin films --- p.49 / Chapter 3.5 --- Discussion --- p.52 / References --- p.53 / Chapter Chapter 4 --- LCMO/Y2O3 and LCM0/Gd203 multilayers / Chapter 4.1 --- Sample preparation --- p.54 / Chapter 4.2 --- As-deposited multilayers --- p.56 / Chapter 4.2.1 --- Structural Characterization --- p.56 / Chapter 4.2.2 --- Transport properties --- p.62 / Chapter 4.3 --- Oxygen annealing --- p.67 / Chapter 4.3.1 --- Introduction --- p.67 / Chapter 4.3.2 --- Post-annealing condition --- p.68 / Chapter 4.4 --- Oxygen post-annealed multilayers --- p.69 / Chapter 4.4.1 --- Structural Characterization --- p.69 / Chapter 4.4.2 --- Transport properties --- p.76 / Chapter 4.5 --- Discussion --- p.85 / References --- p.86 / Chapter Chapter 5 --- LCMO/Y2O3/LCMO trilayer sandwiches / Chapter 5.1 --- Introduction --- p.88 / Chapter 5.2 --- Sample preparation --- p.89 / Chapter 5.3 --- Current-Voltage (I-V) measurement --- p.90 / References --- p.92 / Chapter Chapter 6 --- Conclusion / Chapter 6.1 --- Summary --- p.93 / Chapter 6.2 --- Further work --- p.94

Precast concrete sandwich wall panels (PCSWPs) have been used in the precast industry for decades due to their durability, rapid construction, and thermal efficiency. Shear connectors are used to connect the two wythes of concrete to allow composite action of the system. The use of glass fiber reinforced polymer (GFRP) connectors is a relatively recent breakthrough in PCSWP design. GFRP connectors allow full composite action to occur, while still maintaining the thermal efficiency of the system by not allowing thermal bridging to occur. In order to design concrete sandwich panel systems to act compositely, the engineer must obtain design values from a connector manufacturer, often times making engineers uncomfortable. Shear connectors are typically proprietary and are required to first have design values often times varies by each company. This project aimed to compare existing testing methodologies in order to better inform engineers about design decisions. This project used two methodologies of shear testing on five different types of composite action connectors. Testing was performed using single-shear and double-shear "push-off" tests. In order to gather enough statistical data to compare the testing methodologies, 22 single-shear and 48 double-shear small scale specimens were designed, fabricated, and loaded through failure at the Utah State University SMASH Lab. Testing was performed by applying loads perpendicular to the connectors and measuring the load and amount of deflection that occurred. Using the load-deflection relationships obtained, stiffness values were calculated and recorded for each test. A statistical analysis was performed based on the observed data. This study concluded that the ultimate strength capacity and stiffness of connectors will change depending on the testing methodology used. Single-shear testing will generally provide less ultimate strength and less stiffness when compared to double-shear testing.

In summary, structure-activity relationships in peptide and dendrimer carriers modified with different organometal complexes were studied on a human breast cancer cell line. Variation of the organometal cargo and carrier can significantly influence their biological properties and might open the way to new approaches in chemotherapy. Furthermore, the incorporation of complexes with different C≡O vibrational signatures in a model peptide was explored to examine information encoding in biomolecules in a barcoding strategy for potential imaging applications. In particular for the latter, additional stable metal-carbonyl markers need to be prepared in future work to expand the pool of vibrational labels available. / In der vorliegenden Arbeit konnten also Struktur-Wirkungs-Beziehungen für Organometall-Peptid- und Dendrimer-Konjugate mit unterschiedlichen funktionellen Gruppen an einer humanen Brustkrebs-Zelllinie untersucht werden. Die Variation der Organometall-Gruppen und des Trägermoleküls führen zu signifikanten Unterschieden in ihrer biologischen Aktivität. Zusätzlich wurden Modell-Peptide mit verschiedenen Metallcarbonyl-basierten IR-Markern versehen um diese in einer Barcoding-Strategie zu labeln. In Zukunft soll das Spektrum der verfügbaren, nicht-überlappenden Schwingungsmarker noch deutlich erweitert werden.

Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisor: Jian-Qiao Sun, Dept. of Mechanical Engineering. Includes bibliographical references.

No description available.